The present invention relates generally to welding and, more particularly, to a method and apparatus of controlling output of a welding power source with fused electrode detection.
Welding is a common process to join, combine, or reinforce materials in automotive and industrial environments. The particular welding process chosen depends a great deal on the objective and the products to be joined. For example, stick welding or Shielded Metal Arc Welding (SMAW) is an arc welding process that uses a consumable electrode and may be used with either an AC or DC output. Tungsten Inert Gas (TIG) is another type of welding process and uses a tungsten electrode that does not become part of the completed weld. Both stick and TIG welding, as well as other welding processes, utilize an electrode to create a voltage potential across a welding area.
An electrode is used in the welding process to initiate and maintain a welding arc. For example, in stick welding, the user typically scratches or touches the electrode to a workpiece to begin the welding process. If the open circuit voltage of the power source is sufficient, an arc will be created between the electrode and the workpiece as the user pulls the electrode away from the workpiece. If the electrode is pulled too far from the workpiece, too fast, the voltage necessary to make the arc may not be obtainable and the welding process is not initiated. Conversely, the welding process will continue as long as the open circuit threshold is not exceeded. That is, a xe2x80x9cshortxe2x80x9d is detected and maintained at the weld. This xe2x80x9cshortxe2x80x9d condition is not a true short as a minimal voltage potential exists between the electrode and the workpiece. A xe2x80x9ctrue shortxe2x80x9d would occur when there is not a voltage potential or drop between the workpiece and electrode. Typically, as long as the threshold is not exceeded (i.e. the xe2x80x9cshortxe2x80x9d is maintained), the power source is said to be in a welding state.
During a welding process, if the electrode comes in contact with the workpiece for any more than a brief moment, the voltage potential between the workpiece and the electrode drops and a true short condition is experienced. When this occurs, the electrode becomes fused, or welded directly to the workpiece, and once stuck, is difficult to remove.
A number of controls have been developed that advantageously address disabling the welding output if the open circuit threshold is exceeded. Notwithstanding the advances made in arc-ending detection, there remains a need to control the output of a welding power source based on a fused electrode condition.
Sticking of the electrode to the weld of a workpiece is undesirable for a number of different reasons. For example, if the electrode sticks in the weld, the electrode melts very rapidly and becomes one with the weld. An operator must then twist and turn the electrode to break the electrode from the weld. This not only detracts from the quality of the weld, but also can rapidly consume or destroy the electrode and/or create arcing between the electrode and the electrode holder. This arcing can damage not only the electrode, which in many cases is a consumable, but worse, damage the holder of the electrode. If too much of the electrode is lost due to a fused electrode, the electrode must be replaced. Moreover, an excess amount of electrode consumed in a weld may result in the operator having to grind the weld and restart the weld process anew. Worse, that which was the subject of the welding may also be damaged and in need of replacement. Damage to the electrode and the object welded results in a longer welding process and increased welding/product costs.
It would therefore be desirable to design a system for controlling the output of a welding power source having early fused electrode condition detection. It would also be desirable to implement a fused electrode detection scheme with an arc ending detection circuit to provide a more robust controlled power source.
The present invention is directed to a method and apparatus to control the output of a welding power source having a fused electrode detection circuit overcoming the aforementioned drawbacks. The present invention incorporates a fused electrode detection circuit to regulate the output of the welding system power source. By providing feedback as to when the electrode is stuck in or to the weld, the output of the power source may be regulated to provide a stable environment. By reducing the output of the power source upon detection of a fused electrode condition, the present invention allows a user or technician to quickly remove or un-stick the electrode from the weld. The invention also allows the electrode to be xe2x80x9cunstuckxe2x80x9d with ease by limiting the output of the power source until the electrode is xe2x80x9cunstuckxe2x80x9d.
Therefore, in accordance with one aspect of the present invention, a welding power supply comprising a source of power and a controller connected to the source of power. The power supply includes an output feedback circuit connected to the controller wherein the controller is configured to receive a signal indicative of a fused electrode condition at a welding area and automatically reduces output of the source of power upon receipt of the signal.
In accordance with another aspect of the present invention, a controller is configured to regulate output of a welding power source. The controller includes an output feedback circuit configured to provide a signal indicative of an output condition at a welding area and a control circuit connected to the output feedback circuit. The control circuit is configured to regulate output of the welding power source based on the signal provided by the output feedback circuit. The control circuit is further configured to automatically reduce the output of the welding power source upon receipt of a fused electrode condition signal from the output feedback circuit.
In accordance with a further aspect of the present invention, a computer readable storage medium having a computer program stored thereon is designed to regulate a welding power source. The computer program includes a set of instructions that when executed by a processor causes the processor to receive an input indicating an output condition at a welding area and determine from the input if an electrode is becoming fused in a weld. If such an electrode condition is determined, the computer program causes the processor to automatically output a command signal to the welding power source to reduce power output to a prescribed level until an input indicates a free electrode condition.
According to a further aspect of the present invention, a welding power supply includes means for providing power suitable for welding and means for controlling the means for providing power that is connected to the means for providing power. The power supply further includes means for providing feedback of a welding area. The means for providing feedback is connected to the means for controlling. The welding power supply also includes means for reducing an output of the means for providing power based on reception of a signal from the means for providing feedback of an electrode sticking at the welding area.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.